Center for tapping tools



June 1942- J. N. HARRELL 2,286,088

CENTER FOR TAPPING TOOLS Filed Dec. 4, 1941 2 Sheets-Sheet l J j 'yhz a? P I g If Inventor mZmrreZZ Attorney June 9, 194 2. J. N. HARRELL 2,286,088

CENTER FOR TAPPING TOOLS FiledHDec. 4, 1941 2 Sheets-Sheet 2 i 4- I 1d g i 4 A? 7 ll Inventor @1 2 J1 ErreZZ By @Mm Attorney Patented June 9, 1942 UNITED STATES PATENT OFFICE CENTER. FOR. TAPPIN G TOOLS Joel N. Harrell, Charleston, 8. 0.

Application December 4, 1941, Serial No. 421,654

1 Claim.

My invention relates to improvements in centers for use in drill presses and lathes, the primary object in view being to provide a simply constructed, efficient device this character for 1 tail in the succeeding description, and defined inv the claim appended hereto.

In said drawings:

Figure 1 is a view in elevation, with parts shown in section, illustrating the preferred embodiment of my invention,

Figure 2 is a view in longitudinal section of the center detached,

Figure 3 is a view in end elevation of the center,

Figure 4 is a view in transverse section taken on the line 4-4 of Figure 2, and

Figure 5 is a view in perspective of the centering pin.

Reference being had to the drawings by numerals, my improved center has been shown therein, by way of exemplification, as forming part of the equipment of a drill press, I designating the table of the drill press, 2 the usual upwardly tapering drill chuck above the table I, and 3 a suitable clamp for securing a piece of stock 4 on the table I in a position for the drilling of a, bore to be tapped therethrough.

The center of my invention comprises a tapering shank 5 for insertion upwardly into the chuck 2 and provided at its larger end with an enlarged cylindrical head 6 having at the end thereof opposite the shank 5 a reduced externally threaded nipple I. An internally threaded cap nut 8 is turned onto the nipple I. The head 6 and nipple l are provided with an axial bore 9 or uniform diameter, the shank 5 with a counterbore l0 axially aligned with the bore 9, and the nut 8 with an aperture ll of the same diameter as the counterbore l0 and axially aligned therewith and with the bore 9.

An elongated centering pin I2 is slidably mounted in the aperture l I and counterbore It! for advance and retraction, said pin, as will be understood, being of the same diameter substantially as the aperture II and counterbore I0.

A collar l3 on said pin l2 intermediate the ends thereof and slidably fitting in the bore 8 liifiits advance of the centering pin [2 by engagement of the same with the cap nut 8. A coil spring l4 sleeved onto the center pin [2 between the collar I3 and a shoulder IS in the head 6 tends to advance said pin l2. The center pin I2 is provided with the usual pointed outer end l6.

Referring now to the use and operation of the described center, after the piece of stock 4 is drilled in the usual manner for tapping, the center of my inventionis substituted for the drill, the usual tapping tool I! started into the drilled bore, not shown, for operation as by the usual ratchet wrench l8, and the center pin I2 retracted in opposition to the coil spring l4 and then permitted to seat under the action of said spring in the usual socket 19 in the end of the tapping tool ll, it being understood that such positioning of the center pin I2 is manually effected. As will be clear, with the center pin I2 thus positioned relative to the tapping tool H, the latter will be held axially aligned with the bore to be tapped during the tapping operation, the coil spring [4 causing the center pin to follow the tapping tool I! as it is turned into the bore being tapped.

The foregoing will, it is believed, suflice to impart a clear understanding of my invention without further explanation.

Maniiestly, the invention, as described, is susceptible of modification without departing from the inventive concept, and right is herein reserved to such modifications as fall within the scope 'of the subjoined claim.

What I claim is:

A center for use in a drill chuck or head stock for holding a tapping tool aligned with a bore to be tapped comprising a tapered shank for insertion in said chuck, a cylindrical head on one end of said shank having a reduced threaded nipple on one end thereof, a cap nut threaded onto said nipple, said head having an axial bore therethrough and said shank a counterbore extending axially from said bore of the head and forming at its juncture with the latter an internal shoulder in said head, a centering pin slidable in said nut and counterbore for advance and retraction relative to said head, a collar on'said pin within lar and shoulder to yieldingly advance said pin.

JOEL N. HARRELL. 

